The present invention relates to display devices having significant screen brightness (i.e., luminance) which consume a small amount of electric power, and in particular, to a display driving device which controls a variation of contact/separation directions of an actuator with respect to an optical wave guide plate in response to an input image signal input.
Cathode ray tubes (CRT), liquid crystal devices and plasma display devices are known in the art. Cathode ray tubes are known as normal television receiving devices and monitor devices for computers. Although the screens are bright, they consume much electric power, and the overall depth of the display device relative to the size of the screen is great. In addition there are other problems such as diminished resolution in the peripheral portions of the display image, distorted images and graphics, lack of memory feature and an inability to achieve large scale displays. The reason for this is that the light emission point (beam spot) is broadened where electron beams reach the fluorescent face of the CRT diagonally because the electron beam is significantly deflected when fired from the electron gun that images are displayed obliquely. In addition, there are limits to maintaining vacuum in the large spaces of CRT""s.
While liquid crystal displays have certain advantages such as being reduced in size and consuming little power, the brightness of the screen is inferior and the screen viewing angle is narrow. In addition, they have an additional disadvantage in that the configuration of the drive circuits has become very complex due to the fact that gradation expression (gray scale) is accomplished by changes in the voltage level. For example, when a digital data line is used, the drive circuit is configured to have a latch circuit which holds component RGB data (each 8 bits) for a specified period of time, a voltage selector, a multiplexer which switches the voltage level in response to the gradation number, and an output circuit for adding the data output from this multiplexer to a digital data line. In this case, if the gradation number increases, there is a need for the multiplexer to act to switch many levels, thus making the configuration more complex.
When an analog data line is used, the drive circuits are configured to have a shift register for aligning component RGB data (each 8 bits) successively input in a horizontal direction, a latch circuit which holds parallel data from the shift register a designated period of time, a level shifter which takes the voltage level adjustment, a digital to analog (D/A) converter which converts the data output from the level shifter to an analog signal, and an output circuit for adding the signal output for this D/A analog converter to an analog data stream. In this case, while a designated voltage is obtained in response to gradation by using an operating amplifier in the D/A converter, the use of an operating amplifier which outputs highly precise voltages becomes necessary as the range of gradation expands. This has the disadvantage that construction is more complex and more expensive.
Plasma displays are similar to liquid crystal display devices in that the display does not take up much space. In addition, since the plasma display is a flat surface, it has the advantage of being easy to view. In particular, with an alternating type plasma display, there is the added advantage that there is no need to have a refresh memory due to the cell memory function. However, there is a need to alternately switch the polarity of the voltage and have a continuous discharge in order to maintain the memory function in cells. Because of that, a first pulse generator that generates a sustained pulse in the X direction and a second pulse generator that generates a sustained pulse in the Y direction must be provided in the drive circuits. Thus there is a problem that the configuration of the drive circuits is more complex.
A recently developed display device, shown in FIG. 66, includes an actuator 1000. Actuator 1000 is configured with an actuator unit 1008 that has a piezoelectric/electrostriction layer 1002 sandwiched between an upper electrode 1004 and a lower electrode 1006 formed respectively on the upper and lower surfaces of piezoelectric/electrostriction layer 1002. A substrate 1014 includes a vibrator 1010 and a securing portion 1012. Vibrator 1010 is disposed on a lower part of actuator unit 1008. Lower electrode 1006 contacts vibrator 1010 such that actuator unit 1008 is supported by vibrator 1010.
Substrate 1014 is composed of ceramic. A concave portion 1016 is formed in substrate 1014 and of a size so that vibrator 1010 is relatively thin. A displacement transfer portion 1020 makes the area of contact with optical wave guide plate 1018 a designated size. Displacement transfer portion 1020 is connected to upper electrode 1004 of actuator unit 1008, and in the example in FIG. 66, displacement transfer portion 1020 is located close to optical wave guide plate 1018 when actuator 1000 is in a normal state (unmoved) and is disposed so that it contacts optical wave guide plate 1018 at a distance equal to or less than the wave length of light when in a state of excitation.
Then, for example, light 1022 is introduced from the end of optical wave guide plate 1018. In this case, all of light 1022 is totally reflected in the interior without passing the front face and back face of optical wave guide plate 1018 due to the index of refraction of optical wave guide plate 1018. In this state, a voltage signal corresponding to an image signal is selectively applied to actuator 1000 via upper electrode 1004 and lower electrode 1006. By performing the displacement due to normal and excited states of actuator 1000, the contact and separation of optical wave guide plate 1018 with displacement transfer portion 1020 is controlled. By virtue of this, the scattered light (leakage light) 1024 of optical wave guide plate 1018 is controlled and an image corresponding to the image signal is displayed on optical wave guide plate 1018.
This display device has the following advantages: (1) it reduces power consumption, (2) it increases screen brightness, and (3) when using a color screen, there is no need to increase the number of pixels as compared to a black and white screen.
The peripheral circuits of the display device as described above, shown in FIG. 67, are configured to have a display 1030 which has multiple arranged pixels, a vertical shift circuit 1034 which deduces the number of rows necessary for vertical selection line 1032 (which are common to the pixels comprising one column), and a horizontal shift circuit 1038 which deduces the number of columns necessary for signal line 1036, which are common to the pixels comprising one column. Because of that, the display information (output voltage) output for the pixel groups of a selected row from horizontal shift circuit 1038 is also applied to the pixel groups related to non-selected rows, thus driving unnecessary pixels. Thus, unnecessary power consumption occurs, which is a disadvantage in reducing the consumption of electric power.
In addition, in endeavoring to improve brightness and contrast with such things as memory effect while increasing the row selection number during the vertical scanning interval, there is a need to supply high voltage to the vertical shift circuit. Moreover, there is a necessity to supply at least three levels of voltage, thus making customization of an IC for the vertical shift circuit more difficult. Reducing the size of the IC""s and making them have many outputs becomes difficult, and making displays thinner is hindered by the packaging space of driver IC.
Briefly stated, a display driving device drives a display which includes an optical wave guide plate and a drive section disposed opposite one face of the optical wave guide plate. The display includes a plurality of actuators which control light emitted from specified parts of the optical wave guide plate. The display driving device includes a first drive circuit which applies an offset potential (bias potential) to all actuators, a second drive circuit which outputs a data signal, and a signal processing circuit. The data signal includes a light emitting signal and a light extinguishing signal for each dot in the display, based on an input image signal. The signal processing circuit controls the row electrode drive circuit and the column electrode drive circuit. The column electrode drive circuit controls gradation by a temporal modulation method. Pixel brightness is controlled by the signal processing circuit to decrease the brightness variance between dots caused by the manufacturing process.
The row electrode drive circuit, the column electrode drive circuit, and the signal processing circuit are packaged in the periphery of the display. The row electrode drive circuit is configured so that it supplies offset electrical potential (bias potential) to the row electrodes of all actuators by virtue of a common wire, where each wire and one level of voltage for offset is supplied through the power source. The column electrode drive circuit includes a number of driver outputs corresponding to the total number of dots, and is configured so that it outputs a data signal to each data wire of the display in parallel so that it supplies respective data signals to all dots. Two levels of voltage for data are supplied to each driver output by the power supply.
In a feature of the invention, the signal processing circuit includes a linear correction mechanism for making display properties linear with respect to the gradation level. This facilitates an accurate display and improves contrast, resulting in a sharper image since the display properties change linearly in each dot in response to variations in the gradation level. In current color television formats, gamma correction on the transmitted image (transmission) side is performed to reduce the cost of receivers. This correction becomes unnecessary with a display which uses an optical wave guide as in this invention since the gamma correction is always focused on Braun tubes. Therefore, degradation of resolution of portions of an image with high color saturation does not occur even when displaying a television signal which has been gamma corrected. It is thus possible to evoke the appearance of a crisp display image, because the display properties with respect to the gradation level in the transmission can be corrected linearly.
In a feature of the invention, a light adjustment control mechanism switches the power of a light source in at least two stages at a desired timing in one frame when the display interval of one image is one frame. When applied to a display which uses linear subfields, the brightness level of each linear subfield varies with adjustment of the light source. For example, when the switches of the power of the light source are set to 100% and 25%, linear sub fields which have brightness level 4 and brightness level 1 are defined to correspond to power switch timing of the light source, and when 64 gradations are expressed just by brightness level 1, they can be expanded to 256 gradations. In addition, since it does not use all the power in one frame, consumption of electric power can be reduced.
In a feature of the invention, a preliminary interval separates all dots in one frame with respect to the optical wave guide plate when the display interval of one image is one frame. By virtue of this, there is no degradation of the responsiveness of the separation of the actuator because an image is displayed from the point that all dots are OFF by designating a preliminary interval before the actual image display interval. The preliminary interval is preferably formed coincidental to variations in the output level of the first drive circuit. The yield and reliability of the display is improved.
According to an embodiment of the invention, a display driving device for a display includes an optical wave guide plate which introduces light to the display; a drive section disposed opposite one face of the optical wave guide plate, the drive section including a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots, the drive section controlling a displacement of the plurality of actuators in contacting and separating directions with respect to the optical wave guide plate, the displacement corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the image signal by controlling a leakage light from specified parts of the optical wave guide plate; a first drive circuit which applies an offset potential to all of the actuators; a second drive circuit which outputs a data signal for each dot, the data signal being based on the image signal, the data signal comprising one of a light emitting signal and a light extinguishing signal; and a signal processing circuit which controls the first and second drive circuits wherein one dot is configured by one or more actuators and one pixel is configured by one or more dots, wherein the signal processing circuit controls at least the second drive circuit which in turn controls gradation by at least a temporal modulation method.
According to an embodiment of the invention, a display driving device for a display includes an optical wave guide plate which introduces light to the display; a drive section disposed opposite one face of the optical wave guide plate, the drive section including a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots, the drive section controlling a displacement of the plurality of actuators in contacting/separating directions with respect to the optical wave guide plate, the displacement corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the image signal by controlling a leakage light from specified parts of the optical wave guide plate; a first drive circuit which alternately selects pixels for odd numbered rows and even numbered rows; a second drive circuit which outputs a data signal for each dot, the data signal being based on image signal, the data signal including one of a light emitting signal and a light extinguishing signal; and a signal processing circuit which controls the first and second drive circuits, wherein one dot is configured by one or more actuators and one pixel is configured by one or more dots, and wherein the signal processing circuit controls at least the second drive circuit which in turn controls gradation by at least a temporal modulation method.
According to an embodiment of the invention, a method of driving displays includes introducing light in an optical wave guide plate; providing a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots; providing a drive section disposed opposite one face of the optical wave guide plate which controls a displacement of the actuators in contacting/separating directions with respect to the optical wave guide plate corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the input image signal by controlling leakage light of specified parts of the optical wave guide plate; configuring each dot by at least one actuator; configuring each pixel by at least one dot; applying an offset potential to the plurality of dots; outputting a data signal comprising a light emitting signal and a light extinguishing signal for each dot based on the input image signal; and controlling gradation by at least a temporal modulation method.
According to an embodiment of the invention, a method of driving displays includes the steps of introducing light in an optical wave guide plate; providing a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots; providing a drive section disposed opposite one face of the optical wave guide plate which controls a displacement of the actuators in contacting/separating directions with respect to the optical wave guide plate corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the input image signal by controlling leakage light of specified parts of the optical wave guide plate; configuring each dot by at least one actuator; configuring each pixel by at least one dot; alternately selecting pixels of odd number rows and even number rows; outputting display information to pixels of the selected rows for each dot based on the input image signal, wherein the display information includes a light emitting signal and a light extinguishing signal; and controlling gradation by at least a temporal modulation method.
According to an embodiment of the invention, a display driving device for a display includes an optical wave guide plate which introduces light to the display; a drive section disposed opposite one face of the optical wave guide plate, the drive section including a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots, the drive section controlling a displacement of the plurality of actuators in contacting/separating directions with respect to the optical wave guide plate, the displacement corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the image signal by controlling a leakage light from specified parts of the optical wave guide plate; a first drive circuit which selects dots of designated rows for the plurality of pixels; a second drive circuit which outputs a data signal for each dot, the data signal being based on the input image signal, the data signal including one of a light emitting signal and a light extinguishing signal; and a signal processing circuit which controls the first and second drive circuits, wherein one dot is configured by one or more actuators and one pixel is configured by one or more dots, and wherein the signal processing circuit controls the first and second drive circuits which in turn control gradation by at least a temporal modulation method.
According to an embodiment of the invention a method of driving displays includes the steps of introducing light in an optical wave guide plate; providing a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots; providing a drive section disposed opposite one face of the optical wave guide plate which controls a displacement of the actuators in contacting/separating directions with respect to the optical wave guide plate corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the input image signal by controlling leakage light of specified parts of the optical wave guide plate; configuring each dot by at least one actuator; configuring each pixel by at least one dot; selecting, in turn, dots of all pixels in designated rows; outputting a data signal comprising a light emitting signal and a light extinguishing signal for each dot based on the input image signal; and controlling gradation by at least a temporal modulation method.
According to an embodiment of the invention, a display driving device for a display includes an optical wave guide plate which introduces light to the display; a drive section disposed opposite one face of the optical wave guide plate, the drive section including a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots, the drive section controlling a displacement of the plurality of actuators in contacting and separating directions with respect to the optical wave guide plate, the displacement corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the image signal by controlling a leakage light from specified parts of the optical wave guide plate; a first drive circuit which applies an offset potential to all of the actuators; a second drive circuit which outputs a data signal for each dot, the data signal being based on the image signal, the data signal comprising one of a light emitting signal and a light extinguishing signal; a signal processing circuit which controls the first and second drive circuits wherein one dot is configured by one or more actuators and one pixel is configured by one or more dots; wherein the signal processing circuit includes means for controlling gradation; and wherein the signal processing means includes correction means for correcting brightness to compensate for brightness variations between each of the dots.
According to an embodiment of the invention, a method of driving displays includes the steps of introducing light in an optical wave guide plate; providing a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots; providing a drive section disposed opposite one face of the optical wave guide plate which controls a displacement of the actuators in contacting/separating directions with respect to the optical wave guide plate corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the input image signal by controlling leakage light of specified parts of the optical wave guide plate; configuring each dot by at least one actuator; configuring each pixel by at least one dot; applying an offset potential to the plurality of dots; outputting a data signal comprising a light emitting signal and a light extinguishing signal for each dot based on the input image signal; controlling gradation; and performing brightness correction processing to correct brightness variations between each of the dots.
According to an embodiment of the invention, a display driving device for a display includes an optical wave guide plate which introduces light to the display; a drive section disposed opposite one face of the optical wave guide plate, the drive section including a plurality of actuators arranged corresponding to a plurality of pixels which in turn correspond to a plurality of dots, the drive section controlling a displacement of the plurality of actuators in contacting and separating directions with respect to the optical wave guide plate, the displacement corresponding to attributes of an input image signal, thereby causing an image to be displayed on the optical wave guide plate corresponding to the image signal by controlling a leakage light from specified parts of the optical wave guide plate; each of the actuators including a shape retaining portion consisting of at least first and second layers, wherein the first and second layers are partially separated by a row electrode, and wherein the shape retaining portion is bounded on an upper and lower side by a column electrode; a first drive circuit which applies an offset potential to all of the actuators; a second drive circuit which outputs a data signal for each dot, the data signal being based on the image signal, the data signal comprising one of a light emitting signal and a light extinguishing signal; and a signal processing circuit which controls the first and second drive circuits wherein one dot is configured by one or more actuators and one pixel is configured by one or more dots.